How fast does breast cancer progress in a year?

In Singapore, approximately five women are diagnosed with breast cancer everyday, making it the highest occurring cancer among females here. If you or someone you know have detected a lump or been diagnosed with breast cancer recently, you must be wondering: how long has the cancer been around? Why did it take so long for me to figure it out? Will it spread to other parts of my body?

The truth is, the answers to these questions really depend on the type of breast cancer you have and other factors like its molecular characteristics. This article looks at how quickly breast cancer can progress, the types of breast cancers and long term outlook.

Breast cancer growth rate

Cancer occurs due to a mutation in human cells, meaning cells do not follow normal patterns of cell division. Instead of dying out, old cells grow out of control, forming new, abnormal cells and a tumour. 

As with all cancers, breast cancer progresses by simple cell division. It starts with one malignant cell, which divides and multiplies exponentially — one cell becomes two, two becomes four, and so on. As this happens, the tumour will increase in size. In order for a breast cancer tumour to be felt, it has to divide 30 times — so up to the 28th cell division, both you and your doctor cannot detect it by hand. In terms of years, it’s hard to say exactly how long the cancer has been in your body, but based on how frequent each division happens —one to two months for most cases— it’s likely that the cancer has been around for 2-5 years. 

To add on, by the time you feel a tumour, it’s probably also around long enough for the cells to spread to the rest of the body. Breast cancer is most likely to metastasise to the lungs, bones and lymph nodes. This may sound extremely scary, but in reality what it really emphasises is the importance of breast cancer screenings. Mammograms detect breast cancer even before it’s detected by hand. When detected early, breast cancer is very treatable with a 90% success rate. Find out what is the most suitable screening for you, [Ultrasound or Mammogram].

Types of breast cancers — do they affect how fast the cancer progresses?

One way to estimate how fast a breast cancer progresses is by looking at the doubling time, which is the amount of time it takes for a tumour to grow in size. A 2019 study found that growth differed based on the estrogen receptor status of the tumour. Specifically, certain types of breast cancer like HER2-positive breast cancer and triple-negative breast cancer grew at faster rates. 

A number of different studies have also discovered other factors that contribute to the growth of breast cancer in a year, such as:

In that case, why don’t I jump straight to having an ultrasound then?

• Age at diagnosis
  Breast cancers in younger women tend to be faster and have higher tumour grades.
• Hormonal status
  Breast tumours often grow more aggressively for women who are premenopausal due to the estrogen in the body.
• Receptor status
  Triple negative and triple positive breast cancers generally grow more rapidly than estrogen receptor-positive breast cancers.
• Estrogen treatment
  Women who undergo hormone replacement therapy especially after menopause have breast tumours with a more rapid growth rate.

Stages of breast cancer and their long term outlook (survival rate)

• Stage 0
  Breast cancer at this stage is considered non-invasive, and is only present in the ducts or lobules. The survival rate is close to 100%. 
• Stage 1
  From Stage 1 onwards, breast cancer is invasive. Tumours in Stage 1 breast cancer remain small and are still situated near the primary site. Stage 1A tumours are 2cm or smaller and have not yet reached the lymph nodes; stage 1B tumours have reached the lymph nodes. Survival rate is close to 100%.
• Stage 2
  Tumours may be larger and may have spread to the lymph nodes. Survival rate is 93%.
• Stage 3
  At stage 3, the tumour might already have spread to several lymph nodes but not yet to other organs. Survival rate is 72%.
• Stage 4
  At stage 4, breast cancer has already spread to other parts of the body including the lymph nodes, bones, lungs, brain or liver. Breast cancer at this stage is not curable. Treatment focuses on preventing the cancer from spreading to other parts of the body. Survival rate is 22%.

Depending on the stage, treatment for breast cancer includes local treatments (lumpectomy, mastectomy, radiation therapy) or systemic treatments (chemotherapy, hormonal therapy, targeted therapy). 

References 

• Lee, S. H., Kim, Y. S., Han, W., Ryu, H. S., Chang, J. M., Cho, N., & Moon, W. K. (2016). Tumor growth rate of invasive breast cancers during wait times for surgery assessed by ultrasonography. Medicine, 95(37), e4874. https://doi.org/10.1097/MD.0000000000004874
• Kolak, A., Kamińska, M., Sygit, K., Budny, A., Surdyka, D., Kukiełka-Budny, B., & Burdan, F. (2017). Primary and secondary prevention of breast cancer. Annals of agricultural and environmental medicine : AAEM, 24(4), 549–553. https://doi.org/10.26444/aaem/75943